The Effect of Eye Drops and Applanation Tonometry on Optical Biometry.

Nayer, Zacharia; Bhat, Amar; Sohal, Preet K; Murdock, Braedon; Watson, Shelly H; Belyea, David A

PURPOSE This study aimed to determine if eye drops (phenylephrine, tropicamide, and fluorescein-proparacaine) and Goldmann applanation tonometry (GAT) have an effect on optical biometry measurements for pre-operative cataract surgery workup. SETTING George Washington University, Department of Ophthalmology DESIGN:: This study was a non-randomized control trial METHODS:: Participants over age 18 with no contraindications to eye drops or tonometry were recruited. Optical biometry measurements were obtained on a single eye using the Lenstar LS900. One drop each of phenylephrine, tropicamide, and fluorescein-proparacaine was applied to the same eye and measurements were repeated. GAT was performed, and measurements were repeated. For control subjects, the contralateral eye was also measured at each interval. RESULTS There was no statistically significant difference in mean predicted post-operative refraction (PPOR) K1, K2, or axis post-drops and post-GAT (n = 62). After drops were applied, mean central corneal thickness increased from 540 to 542 (P = 0.0002), mean anterior chamber depth (ACD) increased from 3.68 mm to 3.70 mm (P < 0.0001), and lens thickness decreased from 3.66 to 3.65 (P = 0.001). After GAT, anterior chamber depth increased to 3.76 mm (P < 0.0001) and lens thickness increased to 3.60 mm (P < 0.0001). There was no statistically significant difference in PPOR or other parameters for the control eyes (n=5). CONCLUSIONS GAT and phenylephrine, tropicamide, and fluorescein-proparacaine drops did not affect the primary outcome of PPOR. This suggests that cataract surgery candidates do not need to return for a separate pre-operative visit for optical biometry.